Clint Edwards > RPC-Simple > RPC::Simple

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Module Version: 1.002   Source  

NAME ^

RPC::Simple - Perl classes to handle simple asynchronous RPC calls with call-back

SYNOPSIS ^

Client Side :

    package MyLocal ;
    
    use vars qw($VERSION @ISA @RPC_SUB $tempObj) ;
    @ISA = qw(RPC::Simple::AnyLocal);
    @RPC_SUB = qw(remoteAsk);

    sub new
    {
        my $type = shift ;

        my $self = {} ;
        my $remote =  shift ;
        bless $self,$type ;

        $self->createRemote($remote,'MyRemote.pm') ;
        return $self ;
    }
    sub answer
    {
        my $self = shift ;
        my $result = shift ;

        print "answer is $result\n" ;
    }


    package main ;
    
    use RPC::Simple::Factory ;

    use IO::Socket ;
    use IO::Select ;

    my $verbose = 0 ; # you may change this value to see RPC traffic

    my $factory = new RPC::Simple::Factory(verbose_ref => \$verbose) ;
    my $local = new MyLocal($factory) ;
    $local->remoteAsk(callback => 'answer');

    my $selector = IO::Select->new();
    $selector->add($factory->getSocket());

    my ($toRead, undef, undef) = IO::Select->select($selector, undef, $selector, 10);
    foreach my $fh (@$toRead)
    {
        if($fh == $factory->getSocket())
        {
            $factory->readSock();
        }
    }

Server Side :

    package MyRemote ;

    use vars qw($VERSION @ISA @RPC_SUB) ;
    @ISA = qw(RPC::Simple::AnyRemote);
    @RPC_SUB = qw(answer) ;

    sub remoteAsk
    {
        my $self=shift ;
        my %args = @_;
        my $callback = $args{callback} || undef;

        if (defined $callback)
        {
            $self->$callback("Hello local object");
        }
    }


    package main ;

    use RPC::Simple::Server ;
    use RPC::Simple::Factory ;

    my $arg = shift ;

    my $verbose = 0 ; # you may change this value to see RPC traffic

    my $pid = &spawn(undef,$verbose) ; # spawn server

See t/connection.t and t/RealMyLocal.pm for more information.

DESCRIPTION ^

This module implements remote procedure call. I've tried to keep things simple.

So this module should be : - quite simple to use (thanks to autoload mechanisms) - lightweight

It sure is not : - DCE - CORBA - bulletproof - securityproof - foolproof

But it works. (Although I'm opened to suggestion regarding the "un-proof" areas)

The module is made of the following sub-classes :

 RPC::Simple::Agent - Perl extension for an agent object 
 RPC::Simple::AnyLocal - Perl extension defining a virtual RPC client class

 RPC::Simple::AnyRemote - Perl base class for a remote object 
 RPC::Simple::CallHandler - Perl class to handle RPC::Simple calls with call-back
 RPC::Simple::Factory - Perl extension for creating client
 RPC::Simple::ObjectHandler - Perl class to handle a remote object
 RPC::Simple::Server - Perl class to use in the RPC::Simple server script.
 RPC::Simple::AnyWhere - Common parts for AnyLocal and AnyRemote

Anyway, the casual user should worry only about inheriting the RPC::Simple::AnyLocal class and creating a RPC::Simple::Factory on the local side.

On the remote side, the user will only have to inherit RPC::Simple::AnyRemote and run the mainLoop method of RPC::Simple::Server.

In each side you must declare all methods available on the other side in a global array of your class.

How it works ? The user (i.e. you) must write a local class which inherits from AnyLocal. AnyLocal is designed to handle Agent and Factory.

    AnyLocal --1---<>---1-- Agent --*--<>---Factory----<>--LAN
        |
       /\____
            |
            |
        LocalClass

First, the user script will have to : - instantiate one Factory. - Create its instance of LocalClass - LocalClass::new will call $self->createRemote, this will create the Agent class.

 - Now any call to an undefined method (BUT declared in @RPC_SUB)
of LocalClass will be forwarded to the Remote class.
If this call has a code reference as first parameter, Agent
will call this code when the remote call is over. I.e. all remote
procedure call must be designed in asynchronous mode.

Note that undefined method not declared in @RPC_SUB will lead to an error. Autoloading is no longer supported (unless someone complains loudly).

Note that Factory and Agent can use Tk to manage the socket connection, but thisis no longer required..

On the remote side, the user will write its RemoteClass which will inherit from AnyRemote.

    LAN --1--<>--*-- Server --1--<>--*--ObjectHandler--1--<>--*--CallHandler
                                              |                        |
                                              1                        *
                                              |                        |
                                              --<>--1--AnyRemote--1-<>--
                                                           |
                                                          /\____
                                                               |
                                                               |
                                                          RemoteClass

RemoteClass will be called with the method name that was invoked for LocalClass. RemtoteClass may call a function from local class using the same mechanism but it may NOT expect a call-back from this call to the local side.

Note that the remote class may call directly method from the Local class. (Provided the local method is declared in the @RPC_SUB array of the remote class)

Note that the instance variable of the local class or remote class are not shared or updated or replicated magically. If you must pass data from one side to the other, you have to do it explicitely. In most case you'll pass the variable value as a method parameter.

CAVEATS ^

Well, this stuff is supposed to be pretty simple, the code to handle the RPC and callback is not very complicated, but I sure have a lot of problem to write a doc which make using this module simple. Future version may get better depending on your comments or questions.

THANKS ^

    Mike South <msouth@fulcrum.org>

AUTHORS ^

    Current Maintainer
    Clint Edwards <cedwards@mcclatchyinteractive.com>
    
    Original
    Dominique Dumont, <Dominique_Dumont@grenoble.hp.com>

SEE ALSO ^

perl(1), RPC::Simple::AnyLocal(3), RPC::Simple::AnyRemote(3) .

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